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Rheem code 29 (condensate not draining): what to check

By How House Works EditorialBased on Rheem manualsChecked against sources Updated

Rheem display

29

“Neutralizer is clogged.”

RTGH-3 · RTGH-3 Use and Care Manual, p. 75; RTGH Tankless Easy Installation Guide, p. 7; RTGH-3 and RTG-3 Troubleshooting Manual, p. 43
Owner checks, then technician

The chart row gives only "Contact a dealer or qualified service technician." (RTGH-3 manual, p. 75). We class 29 as mixed because the owner maintenance list in the same manual includes checking the condensate line for blockage and, if a neutralizer is installed, checking its medium once a year (RTGH-3 manual, p. 68). The RTGH EZ guide words the cause "Condensation Trap is clogged." (RTGH EZ guide, p. 7). Troubleshooting manual name: "Condensation not drained from collector": the electrode in the built-in drain trap reads the water level as full, or cannot read it (AP21822 tech manual, p. 43). The RTG-3 chart and the RTG-R-3 troubleshooting manual have no code 29, and AP21822 labels the water level electrode "FOR CONDENSING MODEL ONLY" (AP21822 tech manual, p. 19).

What it means

RTGH-3 heaters are condensing models with a built-in drain trap for condensate. An electrode in the trap senses the water level. If the trap reads full, or the electrode cannot detect the level at all, the heater shows 29 RTGH-3 and RTG-3 Troubleshooting Manual, AP21822, p. 43. The RTGH-3 Use and Care Manual says that if the condensate drain gets blocked, an error code appears and the drain must be cleared RTGH-3 manual, p. 41. Condensate is acidic RTGH-3 manual, p. 64.

Check these first

The chart row for 29 has one remedy: contact a dealer or qualified service technician RTGH-3 manual, p. 75. The owner maintenance list in the same manual covers the drain line and the neutralizer RTGH-3 manual, p. 68, so an owner can check both before the call.

  1. Close all hot water taps. Turn the heater off with the POWER ON/OFF button on the remote control, wait about 5 minutes, turn it back on and open a hot tap. If 29 is still shown, turn the heater off, unplug it for about 30 seconds and plug it back in RTGH-3 manual, p. 74. Keep the heater turned off for the checks below.
  2. Look along the condensate drain line you can see for a blockage. Checking it is on the owner maintenance list RTGH-3 manual, p. 68, and the manual asks owners to inspect the drain line regularly to make sure condensate drains properly RTGH-3 manual, p. 64.
  3. Look at the end of the drain line. Rheem’s installation section says it should be open to the air, not under water or anything else, with the line sloping down toward the end RTGH-3 manual, p. 41. In cold climates the drain may need protection from freezing RTGH-3 manual, p. 41.
  4. If a condensate neutralizer is installed, check that its medium is still there. The owner list calls for this once a year and says to replace the neutralizer if the medium is used up RTGH-3 manual, p. 68.
  5. Restart the heater and open a hot tap. If 29 is still shown, turn the heater off, write down the code and call for service RTGH-3 manual, p. 74.

When to call a licensed technician

  • A clogged neutralizer: the chart sends it to a dealer or qualified service technician RTGH-3 manual, p. 75.
  • Code 29 coming back after the checks above.
  • The troubleshooting manual’s list for 29, written for technicians and service professionals only AP21822 tech manual, p. 7. The first item is the protection plug on the drain connection at the bottom of the unit, which may not have been removed. The others are a blockage inside or outside the drain line, a pinched line, and a “P” trap, which the drain line does not need and which the manual says to remove AP21822 tech manual, p. 43.
  • Do not run the heater without the condensate drain connected and routed to an external neutralizer or to a drain that can handle corrosive condensate RTGH-3 manual, p. 64.
  • Changes to the drain line follow the installation rules: PVC, CPVC or flexible tube only, and no direct connection to the sewer RTGH-3 manual, p. 41.

Notes for different models

Code 29 belongs to the condensing RTGH-3. The RTG-3 chart does not list it RTG-3 Use and Care Manual, p. 77, and the RTG-R-3 Troubleshooting Manual has no section for it. AP21822 covers both RTGH-3 and RTG-3 models, but labels the water level electrode “FOR CONDENSING MODEL ONLY” AP21822 tech manual, p. 19.

The RTG-3 and RTG-R-3 manuals describe a condensate trap for direct-vent models that connects to the vent. Owners are asked to inspect it regularly to make sure it holds enough water and drains properly RTG-3 manual, p. 66; RTG-R-3 Use and Care Manual, p. 63.

IKONIC heaters show A029 for a blocked condensate line and send it to a dealer or qualified service technician IKONIC Use and Care Manual, p. 107. Their manual asks owners to inspect the condensate drain line on a regular basis and to check the neutralizer medium periodically IKONIC Use and Care Manual, p. 94.

Related Rheem codes

  • A029 “Blocked condensate line.”
  • 17 “Leak sensor has detected water.”

All Rheem codes

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Sources

  1. Rheem Manufacturing Company. RTGH-3 Use and Care Manual. AP21820 Rev 06, no printed date; cover title: Super High Efficiency Condensing Tankless Water Heater Use and Care Manual; the same file is posted for Ruud RUTGH models; p. 1 is the unnumbered cover. Accessed Oct 12, 2026.
  2. Rheem Manufacturing Company. RTG-3 Use and Care Manual. AP22009 Rev 06, no printed date; cover title: High-Efficiency Non-Condensing Tankless Water Heater Use and Care Manual; the same file is posted for Ruud RUTG models. Accessed Oct 12, 2026.
  3. Rheem Manufacturing Company. RTG-R-3 Use and Care Manual. AP23962 Rev 02, no printed date; cover title: High-Efficiency Non-Condensing Tankless Water Heater with Recirculation Use and Care Manual; the same file is posted for Ruud RUTG-R models. Accessed Oct 12, 2026.
  4. Rheem Manufacturing Company. RTGH Tankless Easy Installation Guide. AP23365, no revision or date printed; no page numbers printed, pages given are PDF pages. Accessed Oct 12, 2026.
  5. Rheem Manufacturing Company. RTGH-3 and RTG-3 Troubleshooting Manual. AP21822 Rev 02, no issue date printed; cover title: High and Super High Efficiency Tankless Water Heater Troubleshooting Manual; written for technicians and service professionals only (p. 7). Accessed Oct 12, 2026.
  6. Rheem Manufacturing Company. RTG-R-3 Troubleshooting Manual. AP24838 Rev 01, no issue date printed; cover title: High Efficiency Tankless Water Heater with Recirculation Troubleshooting Manual; written for technicians and service professionals only (p. 6). Accessed Oct 12, 2026.
  7. Rheem Manufacturing Company. IKONIC Use and Care Manual. AP22745 Rev 07, no printed date; cover title: Condensing Tankless Water Heater Use and Care Manual; Ruud's S and SR Series pages post Rev 06. Accessed Oct 12, 2026.